For service and parts needs, visit your dealer. You will receive genuine GM parts and GM-trained and supported service people.
Genuine GM parts have one of these marks:

Vehicle Care
California Proposition 65 WarningBody Side Trim Panel Replacement - Left Side
Preliminary Procedure
Remove the rear side door sill trim plate. Refer to Rear Side Door Sill
Trim Plate Replacement.
Remove the rear seat back. Refer to Rear Seat Replacement.
Remove the quarter window garnish molding. Refer to Quarter Window
Garnish Molding Replacement.
...
Keys
WARNING
Leaving children in a vehicle with the ignition key is dangerous and children
or others could be seriously injured or killed. They could operate the power windows
or other controls or make the vehicle move. The windows will function with the keys
in the ignition, and children or other ...
Rear Side Door Outside Handle Rod Adjustment
Removal Procedure
Remove the rear door water deflector as needed. Refer to Rear Side Door
Water Deflector Replacement.
Use a flat-head tool to open the clip from the threaded rod connecting
the lock to the outside handle.
Adjust the travel of the handle by removing the threaded rod ...